That the dog approaches the bed so cautiously would certainly suggest that it knows what it's doing is against the rules. It wants up, but knows that, in the presence of its owners, at least, it is not allowed to. But the coast is clear. The dog hops up anyway, and proceeds to absolutely go to town, exhibiting a joie de vivre that defies anyone to assert, as French philosopher René Descarte once did, that dogs are merely machines.

...dogs have all of the same brain structures that produce emotions in humans. Dogs also have the same hormonesand undergo the same chemical changes that humans do during emotional states. Dogs even have the hormone oxytocin, which, in humans, is involved with feeling love and affection for others. With the same neurology and chemistry that people have, it seems reasonable to suggest that dogs also have emotions that are similar to ours.

Coren cautions that it is "important to not go overboard and immediately assume that the emotional ranges of dogs and humans are the same." There's a strong likelihood this dog is simply engaging in some form of scent marking, an instinctive behavior observed in many mammals. So when I talk about "joy," is there some anthropomorphizing happening here, on my part? Most definitely. Humans love to project human qualities onto animals, and our tendency to do so stretches back far into our past. Some researchers even think that, without anthropomorphism, neither pet-keeping nor animal domestication would ever have been possible.

Why? Because anthropomorphizing non-human animals is fun and useful. Yes, useful.
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But even if its actions are motivated by instinct, this dog looks to me to be having an awfully good time. For the sake of argument, however, let's say it is happy about romping on the bed while its masters are away – would that emotion qualify as complex? Strictly speaking, no. Happiness – like anger, sadness and fear – is defined as a "basic" emotion. But that doesn't necessarily mean that dogs aren't capable of emotional complexity. Here's the American Psychological Association on the subject:

While basic emotions such as anger, surprise or fear tend to happen automatically, without much cognitive processing, the self-conscious emotions, including shame, guilt and pride, are more complex. They require self-reflection and self-evaluation.

While it is clear that we can learn a great deal about dogs from observing their behavior in terms of purely external actions, I think it is time to recognize that we could understand much more from observing how dogs feel. Moreover, we could learn something about our own feelings as well. For in the realm of feelings we can have no sense of superiority. After a lifetime of affectionate regard for dogs and many years of close observation and reflection, I have reached the conclusion that dogs feel more than I do (I am not prepared to speak for other people). They feel more, and they feel more purely and more intensely. By comparison the human emotional landscape seems murky with subterfuge and ambivalence and emotional deception, intentional or not. In searching for why we are so inhibited compared with dogs, perhaps we can learn to be as direct, as honest, as straightforward, and especially as intense in our feelings as dogs are.